1. Field of the Invention
The present invention relates to a conductive ball bonding method and a conductive ball bonding apparatus and, more particularly, it relates to a conductive ball bonding method and a conductive ball bonding apparatus, suitable for performing minute bonding represented by bonding between a bonding pad formed on a slider of a magnetic head and a pad formed on a lead frame. Typical conductive ball is a solder ball, gold ball, or alloy ball.
2. Related Background Art
In the past, a bonding method in which, after spherical solder (referred to as “solder ball” hereinafter) is installed between electrodes, the solder ball is melted by irradiating a laser beam onto the solder ball to achieve electrical connection between the electrodes are also known.
FIGS. 7A to 7C are explanatory views showing steps for achieving the bonding between the electrodes by melting the solder ball using the laser beam irradiation. Incidentally, these figures refer to bonding between a bonding pad formed on a slider of a magnetic head and a pad formed on a lead frame.
In such bonding in the magnetic head, first of all, as shown in FIG. 7A, a slider 1 constituting a magnetic head and a flexor 2 for supporting the slider 1, which are to be bonded to each other, are previously interconnected by using an adhesive so that electrodes thereof are contacted with each other.
A bonding apparatus 3 for achieving the bonding between the slider 1 and the flexor 2 comprises a pick-up nozzle 5 for picking up a solder ball 4 and a laser radiating unit 6 for irradiating a laser beam onto the solder ball 4, and the pick-up nozzle 5 and the laser radiating nozzle 6 are fixed by a connection block 7 and are reciprocally shifted between the magnetic head and a solder ball supplying device 8 by means of shifting means (not shown).
At the time of performing the bonding between the slider 1 and the flexor 2, first of all, the bonding apparatus 3 is shifted toward the supplying device 8, and then, the solder ball 4 is picked up from the supplying device 8 by utilizing the pick-up nozzle 5. After the solder ball 4 is picked up by the pick-up nozzle 5, the shifting means is operated to convey the solder ball 4 to an electrode area 9 where electrodes of the slider 1 and the flexor 2 are contacted with each other, as shown in FIG. 7B, and thereafter, the suction or absorption of the pick-up nozzle 5 is ceased thereby to rest the solder ball 4 on the electrode area 9. Then, as shown in FIG. 7C, after the solder ball 4 is rested on the electrode area 9, the shifting means is operated again to shift the laser radiating unit 6 above the solder ball 4 and then, the laser beam is irradiated onto the solder ball 4 to melt the solder ball 4, thereby achieving connection between the electrodes formed on the slider 1 and the flexor 2 (for example, refer to JP2002-25025A).
As another bonding apparatus using the solder ball, for example, a bonding apparatus comprising a laser light source disposed upwardly and a connecting element provided at its side with a connection piece for supplying a solder ball and wherein, after the solder ball is dropped into the connecting element, the solder ball is melted by the laser light source is also known (for example, refer to JP H11-509375A).
Furthermore, a technique in which a three-layer structure comprising an arranging mask, a shutter mask and a supplying mask is provided and a solder ball is freely dropped from the arranging mask toward the supplying mask by a sliding movement of the shutter mask interposed between the arranging mask and the supplying mask thereby to supply the solder ball on a pad and to perform the bonding is also known (for example, refer to JP H08-236916A).
However, all of the above-mentioned bonding apparatuses have the following problems.
That is to say, in the bonding apparatus (for example, the apparatus shown in FIGS. 7A to 7C) in which the solder ball is used and the pick-up nozzle and the laser radiating unit 6 are provided separately, after the solder ball 4 is rested on the electrode area 9 by using the pick-up nozzle 5, since the solder ball 4 cannot be held at the bonding apparatus side, the solder ball 4 rested on the electrode area 9 may be deviated from the correct position due to disturbance. Thus, there arises a problem that means for holding the solder ball 4 must be provided separately from the product and the bonding apparatus.
Further, the bonding apparatus using the pressure bonding, the bonding apparatus including the pick-up nozzle 5 and the laser radiating unit 6 separately or the bonding apparatus including the laser light source and the connecting element provided with the connection piece only serve to perform the bonding regarding the single electrode, and, thus, if there are a plurality of electrodes, the process must be repeated by times corresponding to the number of electrodes, with the result that it is difficult to enhance the manufacturing efficiency.
Further, in an arrangement in which the laser radiating unit 6 and the pick-up nozzle 5 are shifted simultaneously, since the connecting block 7 is required to be shifted smoothly, introduction of the laser beam from the laser light source to the laser radiating unit 6 must be performed by using an optical fiber or the like. Since a flexible property of the optical fiber or the like is poorer than those of normal fibrous elements, in the view point of endurance of the apparatus, it is not preferable that the optical fiber be used in the arrangement in which deformation such as bending is inevitable.